DVD-R or DVD+R?

*The DVD-R/RW standard was developed by Pioneer, and is used primarily by Apple and Pioneer.  These 'minus' discs can only be written to in one layer on the discs surface. In addition, this format is supported by the DVD forum, but is in no way an industry standard.  DVD-R/RW discs are cheaper than the 'plus' format.

*The DVD+RW format is supported by Philips, Dell, Sony, HP and Microsoft.  These discs can be written to in multiple layers, giving them slightly better and more disc storage than the 'minus' format.  Because of this additional capacity, they are slightly more expensive than 'minus' discs.

CONCLUSION:

DVD-R:  Write once, better for video as widely accepted by home DVD players.

DVD+R:  Write once, BUT data can be added later (not RW, but still accessible).  Better for data as most computer DVD players can read it and you can fill half the disk, then add a quarter, and complete it a year later (as an example).